How?

Do you ever have those moments where you're so upset about something,and there's no one to talk to or no one that'd understand?
What do you do in those moments?
Do you ever have those moments where you're so sad you could just cry but you have no idea why you feel that way?
How do you cheer yourself up when you don't even know what's wrong?
How do you fix a non-existent but existent problem?